PHP supports C-style pre- and post-increment and decrement operators.
Table 10-5. Increment/decrement Operators
| Example | Name | Effect |
|---|---|---|
| ++$a | Pre-increment | Increments $a by one, then returns $a. |
| $a++ | Post-increment | Returns $a, then increments $a by one. |
| --$a | Pre-decrement | Decrements $a by one, then returns $a. |
| $a-- | Post-decrement | Returns $a, then decrements $a by one. |
Here's a simple example script:
<?php echo "<h3>Postincrement</h3>"; $a = 5; echo "Should be 5: " . $a++ . "<br />\n"; echo "Should be 6: " . $a . "<br />\n"; echo "<h3>Preincrement</h3>"; $a = 5; echo "Should be 6: " . ++$a . "<br />\n"; echo "Should be 6: " . $a . "<br />\n"; echo "<h3>Postdecrement</h3>"; $a = 5; echo "Should be 5: " . $a-- . "<br />\n"; echo "Should be 4: " . $a . "<br />\n"; echo "<h3>Predecrement</h3>"; $a = 5; echo "Should be 4: " . --$a . "<br />\n"; echo "Should be 4: " . $a . "<br />\n"; ?> |